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BIOL 102 > Population Ecology > Flashcards

Population Ecology Flashcards

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1
Q

What is ecology?

A

The study of how organisms interact with the environment and each other.

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2
Q

What are some different aspects of ecology?

A

Population ecology, community ecology, ecosystems, and conservation biology.

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3
Q

What does population ecology study?

A

Population growth, dynamics, and predation.

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4
Q

What does community ecology study?

A

How organisms interact with each other (e.g., competition).

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5
Q

What do studies of ecosystems focus on?

A

The impact organisms have on the environment or vice versa, how energy moves through a system, and food webs.

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6
Q

What is the focus of conservation biology?

A

How to best preserve organisms and their environment.

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7
Q

In ecology, how is a population usually defined?

A

A number of individuals in the same place (e.g., deer population in Northern Virginia, mouse population on George Mason, moose population on Isle Royale). It can also refer to larger groupings, such as the human population.

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8
Q

What is population density?

A

The number of individuals per unit area.

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9
Q

Give an example of population density.

A

100 people per square kilometer. In Fairfax (2018), it was 1,129 people per square kilometer (2,925 per square mile).

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10
Q

What is one sampling technique used when individuals cannot be counted directly?

A

Mark-recapture.

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11
Q

How does the mark-recapture sampling technique work?

A

Individuals are caught and marked, then released. Later, individuals are caught a second time. If most individuals caught the second time are unmarked, it indicates a larger population than if they are mostly marked.

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12
Q

What are some other techniques for surveying populations?

A

Following tracks, surveying small areas and extrapolating, surveying from planes, and scat analysis or other animal signs.

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13
Q

What causes changes in population density?

A

Birth, death, immigration, and emigration.

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14
Q

What are dispersal patterns?

A

How organisms are distributed.

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15
Q

Describe a ‘clumped’ dispersal pattern.

A

Organisms occur in clumps, with few organisms between the clumps.

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16
Q

Describe a ‘uniform’ dispersal pattern.

A

Organisms occur in a constant density, meaning there are about the same number no matter where you look.

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17
Q

Describe a ‘random’ dispersal pattern.

A

Organisms are wherever they want to be, with no particular pattern.

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18
Q

How can mathematical models be used in population ecology?

A

To describe how fast a population can grow.

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19
Q

Explain the concept of exponential growth using a bacterium example.

A

A single bacterium multiplies to two, then four, then eight, and so on. This is represented as 2x, where x is the number of times they divide. For example, at the end of 36 hours, bacteria could cover the earth one foot deep.

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20
Q

What did Darwin realize about unlimited population growth?

A

Something stops populations from growing indefinitely, which helped him formulate his ideas of evolution by means of natural selection.

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21
Q

What is the exponential growth model equation?

A

change in timechange in population​=(birth rate−death rate)N

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22
Q

In the exponential growth model, what does N represent?

A

Current population size.

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23
Q

In the exponential growth model, what does r represent and what does its value indicate?

A

r represents (birth rate - death rate), also called the ‘intrinsic growth rate.’ If r>0, the population is increasing. If r<0, the population is decreasing.

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24
Q

What shape curve does exponential growth produce when plotted?

A

A J-shaped curve.

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25
Why don't most populations grow exponentially?
Something has to stop unlimited growth.
26
What is the logistic growth model equation?
change in timechange in population​=rN(K−N)/K​
27
What is the key difference between the logistic growth model and the exponential growth model?
The logistic model includes the extra term (K−N)/K.
28
In the logistic growth model, what happens if K=N?
There is no population growth.
29
In the logistic growth model, what happens if K is much larger than N (K>>N)?
The equation is almost the same as the one for exponential growth, meaning there is a lot of population growth.
30
What does K represent in the logistic growth model?
The carrying capacity, which is the maximum number of organisms the environment can support.
31
Can carrying capacity (K) vary?
Yes, it can vary (e.g., higher in good years, lower in bad years).
32
What shape curve does logistic growth produce when plotted?
An S-shaped curve (similar to Fig. 36.4B, p. 729).
33
What determines the carrying capacity (K)?
Biotic and abiotic factors.
34
Give an example of a biotic factor that determines carrying capacity.
Food (there's only so much food available), predation (too many predators can lower prey population), and disease.
35
Give an example of an abiotic factor that determines carrying capacity.
Weather (dry, hot, or extremely cold conditions can increase deaths), fire, and precipitation.
36
Give examples of factors that can be both biotic and abiotic in determining carrying capacity.
Territory (e.g., songbirds not liking to be too close) and number of nesting sites.
37
What factors have caused population fluctuations in moose on Isle Royale?
Predation, disease, and temperature.
38
What unique factor has affected the wolf population on Isle Royale?
Inbreeding, which has caused bone deformities and other handicaps.
39
Are only wolves and moose affected by the population dynamics on Isle Royale?
No, vegetation is also affected.
40
What is observed about the populations of lynx and hare?
They can be cyclical, with up and down cycles. When there are a lot of hares, there are a lot of lynx, and vice versa.
41
What are some ideas for what causes the cyclical nature of lynx and hare populations?
Hares increasing until they run out of food and dying off (due to reduced grasses), lynx feeding on hares causing the hare population to crash (and subsequently the lynx population to crash), or a combination of these two factors.
42
What are life tables used for?
To understand survivorship for animals, plants, or any other organism.
43
What can be derived from life tables?
Survivorship curves.
44
What do survivorship curves illustrate?
The percentage of organisms alive as age increases.
45
Describe Type I survivorship.
Most individuals survive until late in life.
46
Describe Type II survivorship.
Death rate is constant, meaning individuals die at any time.
47
Describe Type III survivorship.
Most individuals die very early, with only a few surviving to adulthood.
48
What is r-selection?
Organisms with r-selection produce many offspring and invest few resources into individual offspring, hoping some survive. They usually have a very high potential rate of increase.
49
Give examples of organisms that exhibit r-selection.
Roaches, weeds, and clams.
50
What is K-selection?
Organisms with K-selection produce fewer offspring but put a lot more resources into each offspring. They usually have lower potentials for maximum rates of increase.
51
Give examples of organisms that exhibit K-selection.
Humans, elephants, and oak trees.
52
What is the basic problem with human population growth?
The human population has started to grow exponentially.
53
What are the primary reasons for exponential human population growth?
Much better healthcare (decreased death rate), improved nutrition, and sanitation.
54
What has happened to birth and death rates in many parts of the world regarding human population?
Death rates have declined, but in many parts of the world, birth rates have not declined.
55
What is the current global human population and what is it expected to be by 2100?
Currently 7.9 billion, expected to be over 11 billion by 2100.
56
What enormous strains does human population growth put on ecological resources?
Increased need for food production, a supply of clean water for everyone, and increased use of other resources (minerals, energy, raw materials, etc.).
57
Is the current rate of human resource consumption sustainable?
Simply put, no.
58
What are the best estimates for the Earth's carrying capacity (K) for humans?
Somewhere between 10 and 15 billion people, with a recent paper putting it at 10.2 billion.
59
What condition must be met for the Earth to support 10.2 billion people?
We must not consume as many resources as some people are currently consuming.
60
What is another problem related to resource consumption besides overall population growth?
A large disparity in the amount of resources consumed globally.
61
How does the average American's resource consumption compare to someone from India?
The average American uses 50 times more steel, 170 times more rubber and newsprint, 250 times more fuel, and 300 times more plastic.
62
What is an 'ecological footprint'?
The amount of land required to support an individual's resource consumption.
63
What is the approximate ecological footprint for someone in the U.S. versus someone from India or Bangladesh?
Approximately 8.4 hectares (ha) to support someone in the U.S., compared to 0.5 - 0.8 ha for someone from India or Bangladesh.
64
What is the approximate amount of ecologically productive land available per person globally?
About 2 hectares per person.
65
What ethical questions for conservation are raised by human resource consumption?
1) Do we really have to use so much? (Other developed countries use half as many resources as the U.S.). 2) Is it fair? (Do we want the rest of the world to catch up to our level of development, and what happens to the world's resources then?).
66
What is the implication of other countries developing regarding resource strain?
As other countries develop, the strain on resources becomes worse, and there are simply not enough resources for everyone to consume as the U.S. does.
67
What is 'doubling time' in terms of population?
The amount of time needed for the population to double.
68
In what types of countries is doubling time usually highest?
Poorer, less developed countries.
69
Give examples of doubling times for various countries.
Syria: 16.9 years; Afghanistan: 25.4 years; Kenya: 32.7 years; India: 65.4 years; U.S.: 100 years; China: 225 years. CHINA IS THE HIGHEST
70
What is 'age structure' in a population?
The distribution of ages within a population (e.g., percentage of the population between 0-5 years old, 6-10 years old, etc.).
71
How are age structure data arranged?
Into 'population pyramids.'
72
Which countries typically have a 'pyramid structure' in their population pyramids?
Only fast-growing countries.
73
What happens to the population of a country with many children, even if a 'one child per family' rule is implemented?
The population will continue to increase in size due to a time delay, as those children will grow up and have children themselves.
74
When is China's population expected to start decreasing, despite having a one-child policy from 1980-2015?
Around 2030.
75
What is the subject of the case study by Monk et al.?
Vicuñas in the Andes.
76
Where was the study conducted?
San Guillermo National Park, high in the Andes on the western side of Peru.
77
Describe the location of San Guillermo National Park.
It is a very remote area.
78
What are vicuñas related to?
Llamas and camels.
79
Where do vicuñas typically live?
High in the Andes.
80
What is the normal predator of vicuñas?
Mountain lions (pumas).
81
What role do Andean condors play in the vicuña ecosystem?
They often consume vicuña remains; 88% of the condor diet is composed of vicuña leftovers.
82
Why do vicuñas stay on open plains?
It reduces predation.
83
What impact do vicuñas have on grasslands?
They are grazed heavily.
84
What happened to the vicuña population starting around 2015?
A mange outbreak began killing them off.
85
Describe the effects of mange on vicuñas.
High mortality, lesions, infections, and a weakened immune system.
86
What is a possible origin of the mange outbreak in vicuñas, despite the park's remote location?
From domestic animals.
87
What was the initial effect of the mange outbreak on condor food supplies?
Food supplies initially increased, then decreased.
88
What happened to the condors as a result of the mange outbreak?
Condors moved out of the park.
89
What are the dangers to condors that move out of the park?
Poisoning (possibly intentional) of livestock carcasses and eating food from.
90
What caused the mange outbreak in vicuñas, despite the park's remote location?
From domestic animals.
91
What are the dangers to condors that move out of the park?
Poisoning (possibly intentional) of livestock carcasses and eating food from landfills.
92
How did pumas (mountain lions) respond to the decline in vicuña populations due to mange?
They shifted to other foods, such as rabbits and other small mammals.
93
What happened to the vegetation as a result of the mange outbreak in vicuñas?
Vegetation increased.
94
What might happen to small mammals and birds if grasses increase due to fewer vicuñas?
They may increase, as they depend on grasses for cover and food.
95
How might increased grasses help vicuñas if they recover from the mange?
Increased grasses may help them recover.

BIOL 102 (4 decks)

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